U.S. Pat. No. 3,958,851 discloses a connector having an inner conductor to carry a voltage signal and an outer ground conductor. The ground conductor comprises two parts: the first part is a plastic member provided with a metallic coating and directly surrounding the inner conductor, and the second part is a shield member made from a punched conductive blank folded around the first part. The shield member comprises a lug extending from the connector in the longitudinal direction. The lug may be slid over the surface of another ground terminal of another, identical shaped connector in order to provide a good electrical contact. However, a part of the shield member has a rectangular shape, whereas the remaining part has a circular shape, thus a complex folding technique is needed during manufacturing. Furthermore, since the ground conductor comprises two parts the possibilities to miniaturize it are limited: the connector is not suited for application in modern microelectronics in which connectors comprising several shielded terminals within one housing are used and in which cross section dimensions of each shielded terminal are no more than a few millimeters. Moreover, because of the rather large dimensions of the connector the signal loss is too large for very high frequency applications and it is very difficult to design this connector for 50 ohm applications.
Other connectors comprising ground terminals having extending lugs are, for instance, known from FR-A-1.194.558, the additional French patent to this FR-A-1.194.558, and GB-A-626.696. These documents show several embodiments of connectors having extending ground lugs. However, all the embodiments shown in these references comprise ground terminals having at least two parts and are, therefore, similarly not suitable for miniature applications. Moreover, they only show circular shaped connectors of rather large dimensions, permitting large signal losses in very high frequency applications.
Another connector having extending ground lugs is disclosed in EP-A-0.414.495, in which coaxial terminals within a connector are described as having conventional circular cross-sections. Each connector may comprise more than one coaxial terminal, designed to be connected to a corresponding coaxial terminal of another connector. The signal conductor of the coaxial terminal terminates either in a male or in a female structure. The shape of the end of the ground contact of the terminal varies according to the terminal type: in a terminal whose signal conductor terminates in a male structure, the ground contact has four projecting lugs, while in the case of a terminal whose signal conductor terminates in a female structure, the ground contact has a closed cylindrical form which can be pushed into the four lugs of the ground contact of the first-mentioned terminal. Therefore, the connectors disclosed by prior art require the fabrication of various types of ground contacts, depending on the type of terminal for which the ground contact is intended. In this particular prior art connector, a design of the coaxial terminal is shown to bend through an angle of 90.degree.. The ground contact of this design is obtained from a ground contact blank, which is punched from a flat plate and which, via folding over various small plates and via clamping lugs, provides a substantially electrically enclosed envelope. The various folding steps make a design of this type vulnerable to incorrect alignment and thus to impedance mismatch. Moreover, in this known coaxial terminal the signal terminal is soldered to the signal conductor. Soldering electrical connections, however, is time-consuming and relatively expensive. The known design is suitable for impedances of approximately 75.OMEGA..